Irrigation is generally performed by means of uncovered ditches or by spraying water into the air, in which case the ground becomes wet on the surface. In warm weather the evaporation is high, which leads to a great loss of water. In hot climate and in areas where there is a shortage of water this method can not be applied and the ground dries up. If the water could be led directly to the roots below the ground in the growing depth of the plants, the need of water could be minimized. This has been attempted by using a perforated pipe but when an ordinary perforated pipe is used there is a leakage in direct proportion to the length of the pipe thus restricting the use of this method. In addition, the open perforation are clogged easily.
A buried irrigation pipe is also used, said pipe having through incisions in the longitudinal direction of the pipe so that with low pressure the incisions will stay closed in which case the pipe can also be used for moving the water. When the pressure increases, the incisions will open letting the water flow through the incision into the surrounding ground thus irrigating it. The pipe functions particularly well when it is new and when the water is absolutely pure but when the pipe deteriorates and the accumulation of impurities from the water in the pipe can not be avoided, malfunctions in the closing of the incisions also appear. It is characteristic of the incision in the pipe that when the pressure increases and the incision opens, it will become larger on the inside and more closed on the outside. From this follows that the impurities will be wedged into the incision, in which case at first sporadic dirt will restrain the incision from closing and finally, when a certain amount of dirt has been accumulated, the incision will clog and the pipe will become useless.